Selector panel



J. KOSMIS SELECTOR PANEL v 3 Sheets-Sheet 1 Filed Aug. 7, 1967 Feb.24,1910 J. K SMIS 3,497,131

SELECTOR PANEL Filed Aug. '7, 1967 S Sheets-Sheet 2 3 g- 6i; m 3

4 Feb. 245.1970 j I J. KOSMIS H ,497,1

SELEcTOR PANEL Filed Aug. 7, 1967. 3 Sheets-Sheet, s

United States Patent US. Cl. 235-55 8 Claims ABSTRACT OF THE DISCLOSUREA selector panel for use in a voting machine comprises a selectormechanism having at least one series of depressable selector buttons,each of which is provided with a stern. A guideway extends along theends of the stems of a series of the buttons, and has openings throughwhich the end of the stem of each button projects into the guideway whenthat button is depressed. The width of each such opening, measuredlaterally of the guideway, is less than the lateral width of theguideway. A plurality of spacing members which are longitudinallydisplaceable in the guideway to permit the end of a stem to enter theguideway, are adapted to fill the guideway, after a predetermined numberof keys in the series have been depressed, to prevent any further keysin the series from being depressed. These spacing members include aplurality of elongated cylindrical rollers which extend laterally in theguideway across the openings that admit the ends of the stems. Two ofsuch rollers are normally positioned opposite the end of each stem topermit the end of the stem to penetrate between the two rollers when thecorresponding button is depressed.

BACKGROUND OF THE INVENTION The presnt invention relates to a selectorpanel for use in a registering device or similar device, comprising aselector mechanism, having at least one series of selector buttons, thestem of each of these buttons having a cam or wedge portion cooperatingwith a pair of elements movable apart by depression of the button, saidpairs of elements being received in a common guideway means and beingmovable longitudinally therein to such an extent that a limited memberof selector buttons can be actuated at a time.

Selector panels of this type are used e.g. in voting machines. In aWell-known construction of such a selector panel the elements of theguideway cooperating with the stems of the selector buttons are in theform of balls, which are longitudinally freely movable in the guidewaybetween fixed abutments at the two ends of the guideway. The diameter ofthe balls is large in comparison to the thickness of the stems of thebuttons, which is necessary to prevent the balls from entering eitherpartially or completely into the openings through which the button stemspass into the guideway, which would lead to disalignment of the balls.Due to the relatively large diameter of the balls the selector buttonshave to be depressed a relatively large amount, while the balls arerelatively heavy. The relatively large weight of the balls will bedisadvantageous, particularly with a selector panel comprising a largenumber of selector buttons, in which case the depression of at leastsome of the buttons may be difficult in view of the relatively largetotal weight of the balls to be displaced.

SUMMARY OF THE INVENTION One object of the invention is to provide animproved selector panel avoiding the above drawbacks of the wellknownselector panel and making it possible to extend the number of selectorbuttons in each series at will, while maintaining accurate and easyoperation and actuation of all of the selector buttons.

To this end according to the present invention the elements cooperatingwith the selector button stems are constituted by relatively thin,preferably cylindrical smooth elements, which are longitudinally pressedagainst each other in said guideway by 'means of a spring-loaded plugmember at at least one end of the guideway means and extendingtransversely slightly beyond the lateral confining edges of the openingswhich receive the button stems. The relatively thin elements as proposedby the present invention may have a total weight which is only afraction of that of the ball elements in the well-known construction. Inthe case of thin rollers, which is the preferred form of the elements,undesired turning movements of the rollers in their planes are preventedbecause the rollers are resiliently pressed again each other.

A further object of the invention is to provide a selector panel of thetype referred to in which the guideway may be simply lengthened orshortened in accordance with the number of selector buttons, which areneeded. To this end the guideway means is composed of separate elementssecured to a common base and joining each other along surfaces which areoblique with respect to the longitudinal axis of the guideway. Thus theguideway may be given a larger or smaller length by simply securing alarger or smaller number of guideway elements to the common base.

In case rollers are used as runner elements in the guideway the axes ofthese rollers cross the joints between the individual guideway elementsso that there is no danger of the rollers moving out of their path byentering partially into the joints between the guideway elements.

According to a further feature of the present invention at some points,e.g. at one end, the guideway is penetrated by a blocking memberconnected to a main selector button and having an escape recess(es),said blocking member normally, i.e. when the main selector button isreleased, blocking the rollers in the guideway but upon depression ofthe said main button presenting its escape recess(es) to the adjacentroller(s) which thus far may enter this (these) escape recess(es) so asto make it possible to depress a limited number of the other (ordinary)buttons.

Still further in accordance with the invention the main selector buttonmay cooperate with a pair of rollers in a guideway element extendingtransversely to the other guideway, the rollers in said guideway elementbeing movable apart transversely to the direction of the movement of theother rollers in the other guideway, and being captured in said guidewayelement between plug members extending just beyond the lateral ends ofsaid guideway element.

The latter construction makes it possible to put, in a manner known perse, a plurality of series of selector buttons as columns in side by siderelationship, whereby the guideway elements associated with the mainselector buttons of the columns are coupled by means of the plug membersof said guideway elements acting as coupling members.

The guideway elements associated with the various main selector buttonsmay form a main guideway, in which the pairs of rollers and couplingmembers are ca tured between a spring loaded plug member at one end ofthe main guideway and another spring loaded plug member at the other endof the main guideway, the latter plug member being adapted to be lockedin its innermost position.

In this way a selector panel of simple and reliable construction isobtained, comprising a number of side by side columns, which can beoperated by first selecting a certain column bydepressing the associatedmain selec-- selected.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view ofa selector panel according to the present invention, applied in a votingmachine;

FIG. 2 is a rear perspective view of the inner structure of one selectorcolumn, some of the interior parts being broken away and the surroundingbox or casing being completely removed for purposes of clarity andsimplicity, a main selector and an ordinary selector button taking theirdepressed position and portions of an adjacent selector column beingrepresented in exploded condition;

FIG. 3 is a vertical sectional view of the lower end part of theguideway in a selector column;

FIG. 4 is a side view of a selector button with an associated lockingarm;

FIG. 5 is a horizontal sectional view of the left end part of thehorizontal main guideway shown in FIG. 2;

FIG. 6 is a perspective view showing a part of the upper horizontallocking bar, cooperating with the upper end portion of a verticallocking bar;

FIG. 7 is a horizontal sectional view, showing a number of selectorbuttons belonging to separate columns; and

FIG. 8 is the electrical wiring diagram showing the solenoids andswitches applied in the voting machine.

With reference to FIG. 1, 1 represents the front panel of a votingmachine, said panel being principally constituted by a large number ofselector buttons 2, which are arranged in side by side columns 3. 4indicates the voting button and 5 designates a pilot light.

The selector buttons 2 belonging to each of the individual columns aremounted in a frame 6 (FIG. 2) which in turn is guided and locked inplace in a manner known per se as a tray within the frame (not shown) ofthe voting machine.

Behind each column 3 of selector buttons there is a guideway 7containing rollers 8 movable therein. In the embodiment shown theguideway 7 consists of a number of individual elements 7a joining eachother along surfaces 9 which are oblique relative to the longitudinalaxis of the guideway so that the joints between the successive guidewayelements 7a are crossed by the axes of the rollers 8. The guidewayelements 7a the number of which, in the embodiment shown, equals thenumber of the selector buttons 2, are secured (by fastening means notshown in the drawing) to a vertical wall portion 10 of the column frame6.

The guideway 7 is closed at its lower end by a plug member 11 having ashape which is complementary to the cross-sectional shape of theguideway. The plug member 11 is urged into the guideway by a spring 12but can be displaced outwardly (e.g. a distance of about 1.5

locking arm 15, an abutment face 15a (FIG. 4) of which serving to limitthe outward (releasing) movement of the selector button and for thatpurpose cooperating with an abutment pin 16 projecting from a bar 17,which is fixedly secured to the respective column frame 6 in anysuitable manner. At its free end the locking arm 15 has a cam surface15b disposed at an angle relatively to the direction of depression ofthe selector button 2 and cooperating with one of the projecting pins 18of a locking bar 20 which is movably mounted in the direction indicatedby the arrow I and urged into its upper position by a spring 19. Thelocking bar is guided adjacent its upper and lower ends in guidingbrackets 22 secured to a sidewall portion 21 of the column frame 6.

The pins 18 of the locking bar 20 project through slots 23 in thesidewall portion 21. When a selector button 2 is depressed the slopingcam surface 15b of the locking arm 15 moves past the associated pin 18of the locking bar 20 and thereby causes said pin to move downwards, sothat the locking bar 20 is displaced downwardly against the action ofthe spring 19 until the pin 18 is allowed to move upwardly again, intoengagement with the abutment surface 15a. Thus the depressed button islocked in its depressed position (see the button indicated at A in FIG.2). When after this another selector button of the same column isdepressed, the locking bar 20 will be moved downwardly by the slopingcam surface of the locking arm of that button. As a result of this thepin 18, which up to that time was held locked, is disengaged from theabutment surface 15a of that first button, so that this first button isallowed to return to its initial position by the action of itsassociated spring 13a. Thus each time a selector button is depressed apreviously depressed selector button is released from its depressedposition and allowed to return to its inoperative position. This meansthat a selection made as a result of the depression of a certainselector button of a column can be corrected by I depressing anotherselector button of the same column.

millimeters) against the action of this spring when a selector button isdepressed as will be more fully explained hereafter (FIG. 3).

The guideway elements 7a each have a hub-like portion 13 with a centralopening 13b having a non-circular cross-section in which thecorrespondingly shaped (i.e. square) stem 14 of an associated selectorbutton 2 is guided. The width of each such opening, measured laterallyof the guideway, is less than the lateral width of the guideway 7, andthe cylindrical rollers 8 areelongated and extend laterally in theguideway 7 across such openings. The hub-like portions 13 of theguideway elements 7a are surrounded by coiled springs 13a, urging therespective selector buttons 2 outwardly.

With the exception of the uppermost selector button, which will bedescribed separately, all of the other selector buttons of each of thecolumns are provided with a The guideway 7 is closed at its upper end bya plug member 24, which is urged downwardly by a spring (not shown) intothe guideway and the upper end of which normally contacts a blocking bar26, connected with the uppermost selector button of the column, whichbutton has been indicated by H and is to be seen as the main selectorbutton of the column.

Normally, when none of the ordinary selector buttons 2 is depressed, therollers 8, which function as spacing members, and which are rounded offat their ends, are captured between the plug members 11 and 24 withoutany clearance between the successive rollers as may be seen from thedrawings. The free ends 14a of the stems 14 of the selector buttons 2are wedge-shaped.

In order to enable a certain selector button to be depressed thewedge-shaped end 14a of the stem of that button must be allowed topenetrate transversely through the guideway, to which end it isnecessary that the rollers which are above and under that location inthe guideway move upwardly and downwardly respectively. The downwardmovement is always possible, because the lower plug member 11 can bemoved outwardly against spring action. The upper plug member 24 however,normally i.e. when the main button II is not depressed, abuts theblocking bar 26 and consequently is not allowed to move upwardly. Such amovement is permitted only after depression of the main selector button,whereby a recess 26a of the blocking bar 26 is moved into alignment withthe plug member 24, into which recess the plug member 24 may escapeunder the action of a force applied to it via the rollers 3 by the uppersloping surface of the wedge-shaped end 14a of the stem of the depressedordinary selector button.

In this connection it is to be understood that the first part of thedepression stroke of a selector button is a lost motion, in the sensethat the wedge-shaped stem end 14a of a button will engage the rollersin the guideway only after a certain initial depression. This lostmotion is needed in order to cause a previously depressed selectorbutton, if any, to return to its inoperative position and to disengageits stem from the guideway in the above manner. Only thereafter theguideway is free for penetration by the stem of the new selected button.

By carrying out one of the selector buttons of a column as a mainselector button II the possibility is obtained to select first a certainlist from a number of selection lists or parties which are eachrepresented by a column, by depressing the main selector button of therespective column, after which from the selected list or party a certaincandidate is selected by depressing the selector button associated withsaid candidate from the column which has already selected and deblockedby the previous depression of the main selector button of said column.

The guideway element 7b associated with the main selector button II isdisposed transversely to the guideway 7 and constitutes, together withthe guideway elements associated with the main selector buttons of theother columns, a horizontally disposed main guideway or connectingguideway VII. In each guideway element 711 of this main guideway thereis at least one pair of rollers 27, cooperating with the wedge-shapedstem end of the associated main selector button II.

The guideway elements 7b have their end faces perpendicular to thelongitudinal axis of the guideway VII. The space between each twoguideway elements 7b is bridged by coupling members 28 which areslidably mounted in said guideway elements and project beyond theopposing end faces of the two guideway elements. In the embodiment shownin the drawings the main guideway constituted by the elements 7b isclosed at its left end by the coupling member 28 projecting at that endbeyond the utmost left guideway element 7b. The latter coupling member28 (FIG. 5) is arranged in a manner similar to the plug member 11 at thelower end of the vertical guideway and thus may move a certain distanceoutwardly from the left end of the horizontal main guide way, againstthe action of a spring 25, to enable the depression of a main selectorbutton II. The spring 25 is housed in a block 25a which may be part ofthe frame of the voting machine.

At its right end the main guideway is closed by the coupling member 28projecting at that end beyond the extreme guideway element 712. Thelatter coupling element bears on a blocking lever 31 which is pivotallymounted on a pin 30 fixed to a part 29 of the frame of the machine, thefree end of said lever being shaped as a gear segment 32, whichcooperates with a blocking catch or pawl 34, which is movably guided ina direction indicated by the arrow P and which forms part of thearmature of a solenoid 33. The blocking lever 31 is urged to the left bya spring 36. In the position shown in FIG. 2 the armature of thesolenoid 35 takes its upper position in which the blocking catch 34engages the gear segment 32 of the blocking lever 31. Thus the blockinglever 31 is blocked in its extreme left position.

In the horizontal main guideway the rollers 27 and the coupling members28 are bearing one against the other and captured without clearancebetween the extreme left and right coupling members 28. In the positionshown in FIG. 2 in which the blocking lever 31 is blocked in its extremeleft position, the extreme right coupling member 28 is not permitted tomove to the right, which means, that in that condition none of the mainselector buttons II can be depressed. This also means that none of theordinary selector buttons 2 can be depressed either.

When, however, the armature and the blocking catch 34 connected with itare moved into their lower position as by energizing the solenoid 33,the blocking lever 31 and thus the extreme right coupling member 28 canbe moved to the right against the action of the spring 36. In thatcondition one of the main selector buttons II can be depressed, afterwhich the column of buttons associated with that main button is releasedfor further selection. When depressing the said main selector button thewedge-shaped stem end of that button penetrates between the respectivepair of rollers 27, thereby moving these rollers apart, the left rollerof the said pair moving to the left together with the extreme leftcoupling member 28 and the right roller of said pair movin to the righttogether with any further rollers and coupling members at the right sidethereof, and swinging the blocking lever 31 to the right. The distancewhich can be covered by the blocking lever 31 when moving from itsextreme left position to the right is such that only a limited number ofmain selector buttons II, in this example only one single button, can bedepressed simultaneously before the spacing members 27 and 28 completelyfill the main guideway.

By the depression of a certain main selector button II the voter in thefirst place has selected a certain party, while by the subsequentdepression of one of the ordinary buttons 2 of the column associatedwith the depressed main selector button a certain candidate of saidparty has been selected. For counting the number of votes on each party,as well as for counting the number of votes on a certain candidate ofthat party each of the selector buttons 2, II cooperates with a counter35, an actuating member 37 of which cooperates with the wedge-shapedstem end 14a of the associated selector button.

For claritys sake one counter has been represented only. The depressionof a certain selector button, however, does not yet result in actuationof the counter. The depression of the button merely results in that theactuating member 37 of the counter in question is moved into a positionof preparation of the counting operation. More specifically theactuating member 37, by the depression of the associated selectorbutton, is subject to a rectilinear displacement against the action ofthe spring 38 in a guide block 39 pivoted about a pin 39a. The propercounting operation is effected by actuating a separate member, which isconstituted by a counting bar 40 which is common to all buttons of acolumn and which is provided with projecting pins which may eachcooperate with an actuating member of a counter in the said position ofpreparation to effect the counting operation. To this end the countingbar 40 is mounted for vertical sliding movement in bearings 40a securedto the wall portion 10 of the column frame. A spring 42 surrounding theupper end part of the counting bar 40 urges this bar into its lowerposition. By moving the counting bar 40 upwardly against the action ofthe spring 42 an additional movement is given by one of its projectingpins 41 to the prepared actuating member of the counter associated withthe depressed selector button II and the depressed ordinary selectorbutton 2, said additional movement in this example being an upwardswinging movement about the pivot pin 39a, as a result of which theoperative end 37a of the actuating member 37 moves the small gear 35a ofthe associated counter 35 through a unitary angle.

The other pins 41 remain disengaged from the actuating members of theother counters which have not been placed in a position of preparation.The upward movement of the counitng bar has to take place after thechoice has been definitely made and is effected by the depression of thevoting button 4. The depression of the voting button 4 causes anactuating rod 43 arranged under the column 3 to move to the left as seenin FIG. 2.

Under each of the columns 3 there is a cam 44 carried by the actuatingrod 43, cooperating with a projectlng pin 45 on the end portion of thecounting bar 40, projecting beyond the lower end of the column. When theactuatin rod 43 is moved to the left the projecting pin 45 may be urgedupwardly by the cam 44 together with the counting bar 40, resulting inthe counting operation explained above. This cooperation between cam 44and projecting pin 45, however, only occurs with the selected column.For the counting bars 40 are not mounted for vertical movement only butalso for movement between two angular positions. Normally, i.e. when themain selector button II of a given column is not depressed, the countingbar of the column takes an angular position in which the pins are out ofthe paths of the actuat ng members 39 of the counters 35 and in whichthe projectin pin 45 is out of the path of the associated cam 44. Onlywhen the main selector button 11 of the column is depressed the countingbar is moved into its second, operative angular position in which thepin extends into the path of the actuating member 39, as far as thelatter has been placed in its position of preparation and in which thelowermost projecting pin 45 extends in the path of the associated cam44.

For this purpose the blocking member 26 carried by the main button IIhas a bifurcated crank pin 46 adjacent its free end, which crankcooperates with an additional projecting pin 47 of the counting bar 40so as to move this counting bar through an angle (of about 90 in thisembodiment) into its operative angular position. This construction hasthe advantage that for the final voting operation, whereby the vote isadded to the number of votes, counted in previous selecting and votingcycles, only the counting bar of the selected columns needs to beactuated. Thus the friction to be overcome is minimized, promoting alight and reliable operation of the selection mechanism. The upwardmovement of the counting bar 40 just described is accompanied by adownward movement of the locking bar 20, as a result of which thedepressed selector button 2 is released and may return to its initialposition, ready for a following selection. To this end the movement ofthe counting bar '40 is transmitted to the locking bar 20 by means of abell crank lever 48 pivotally mounted on a fixed pin 48a under theassociated column 3. The bell crank lever 48 engages a projecting pin 49of the extension 20a of the locking bar 20 extending beyond the lowerend of the column and further engages a projecting pin 50 on the lowerend portion of the counting bar 40, the latter pin being advantageouslyintegrally formed with the projecting pin 45.

The distance covered by the locking bar 20 in its downward releasingmovement just described, is larger than the distance covered by thelocking bar under the action of the cam surface 15b of the locking arm15 when depressing the button.

The downward unlocking movement of the locking bar 20 is attended bysimilar unlocking movement of an upper horizontal locking bar 51, whichis similarly provided with projecting pins 52, cooperating with lockingarms 53 carried by the main selector buttons II so as to lock anactuated main selector button II in its depressed position. Fortransmitting the unlocking movement of the vertical locking bar 20 tothe horizontal locking bar 51 a wedge member 54 (FIG. 6) is providedadjacent the upper end of the vertical locking bar 20, said wedge memberbeing adapted to engage an additional projecting pin 55 of the lockingbar 51 when the said downward unlocking movement of the locking bar 20is taking place, as a result of which the locking bar 51 is caused tomove to the right, thereby releasing the depressed main selectorbutton(s), so that the main selector button(s) can return to its (their)initial position, ready for a following selection.

In the embodiment shown in the drawings the depression of the votingbutton 4 effects energizing of the solenoid 57 as a result of which thearmature 57a, as seen in FIG. 2 is pulled to the left, thereby takingthe actuating rod 43 along against the action of a spring 56 through acoupling pin 58. When releasing the voting button 4 the spring 56 causesthe actuating rod 43 to return to its initial position.

Simultaneously with the voting operationi.e. by

depressing the voting button 4-the machine should be put in a conditionin which it is impossible to actuate the machine again after havingreleased the voting button. For this purpose the actuating rod 43, whilemaking its operative stroke, causes a switch S1 to open, as a result ofwhich the energizing circuit of the solenoid 33, which had beeninitially closed by the official of the voting bureau as by depressing apush button switch D and had been kept closed through the switch S1 andthe hold contact H of the solenoid 33, is opened again, therebypermitting the locking pawl 34 to move upwardly so as to lock theblocking lever 31 in its extreme left position as soon as the latter hasreturned to this position upon release of the main selector button II.The electrical wiring diagram of FIG. 8, which shows the switchesmentioned above as well as the solenoid 33, also comprises the solenoid57 associated with the actuating rod 43, which solenoid may be energizedby closing the push button switch constituting the voting button 4.

Preferably each column comprises a switch K1, 2 n, which has to beclosed first before the solenoid 57 associated with the actuating rod 43can be actually energized. In this way the voting button is preventedfrom being effectively actuated until a selection between the (ordinary)buttons of the selected column has been made. It will be understood thatthese switches can be suitably mounted in the respective columns andthat they might be actuated e.g. by the upper plug members 24 in theguideways 7.

The above voting machine can be easily adapted to any occurring numberof parties or lists as well as to any occurring number of candidates ofeach party or list. The adaption to the number of parties or lists canbe simply effected by putting more or less columns 3 including selectorbuttons 2 and counters as trays side by side in the frame of the votingmachine, While the vertical guideways 7 can be easily lengthened orshortened at will by adding or removing guideway elements 7a.

If desired, the various locking bars, counting bars and actuation rodscould consist of sections, in which case these parts of the machinecould be lengthened or shortened at will also.

In the embodiment shown, certain buttons or series of buttons can bemade completely ineffective, if desired, by means of an eccentric 59mounted on each of the guideway elements 7a and 712, said eccentricbeing angularly movable in a plane perpendicular to the longitudinalaxis of the vertical guideways between an inoperative position (markedby X in FIG. 7) and an operative position (marked by Y in FIG. 7). Tomove the eccentric 59 of a certain button 2 from the position X into theposition Y the eccentric has to pass through the space alongside of therelative column which is possible only after removal of a filling strip60 by which the said space is normally filled up. As has beendiagrammatically shown in FIG. 1 the filling strips 60 are locked inplace at their upper ends by means of a common locking rod 61 extendingthrough openings (not shown) in the upper end portions of the strips andslidably mounted in the frame of the machine. The locking rod 61 may bepulled out to unlock the strips 60 for removal from the spaces betweenthe columns 3 so as to render one or more selector buttons ineffectiveor additionally effective respectively by shifting the associatedeccentrics.

I claim:

1. A selector panel for use in a voting machine, comprising a selectormechanism having at least one series of depressable selector buttons,each of which is provided with a stem; a guideway, extending along theends of the stems of a series of the buttons, and having openingsthrough which the end of the stem of each button projects into theguideway when that button is depressed, the width of each such opening,measured laterally of the guideway, being less than the lateral width ofthe guideway; and a plurality of spacing members which arelongitudinally displaceable in the guideway to permit the end of a stemto enter the guideway but which fill the guideway, after a predeterminednumber of keys in the series have been depressed, to prevent any furtherkeys in the series from being depressed, wherein the improvementcomprises a plurality of such spacing members in the form of elongatedcylindrical rollers which extend laterally in the guideway across saidopenings, two of such rollers being normally positioned opposite the endof each stem to permit the end of the stem to penetrate between the tworollers when the corresponding button is depressed.

2. A selector panel according to claim 1 wherein the guideway iscomposed of a plurality of separate elements having mating surfaceswhich are oblique relative to the guideway.

3. A selector panel, according to claim 1 comprising a blocking memberwhich, in its normal position, blocks the spacing members againstdisplacement in the guideway, and a depressa-ble main selector buttonwhich is connected to the blocking member to move the blocking member,when the main selector button is depressed, into a nonblocking positionwhich permits displacement of the spacing members in the guideway.

4. A selector panel according to claim 3 wherein a plurality of seriesof selector buttons are provided with parallel guideways, and a seriesof main selector buttons are provided with a main guideway extendingtransversely to the other guideways.

5. A selector panel according to claim 4 wherein the spacing membersinclude two plug members, arranged at the ends of each guideway, whichare spring biased toward one another.

6. A selector panel according to claim 5 wherein the plug member at oneend of the main guideway is adapted to be locked in its innermostposition.

7. A selector panel according to claim 6 comprising a solenoid having anarmature which is normally biased to lock the plug member at one end ofthe main guideway in its innermost position, an energizing circuit whichcan be closed to energize the solenoid and release the plug member, thesolenoid being provided with self-holding contacts which are closed whenthe solenoid is energized, and a second solenoid which is supplied withcurrent through pairs of contacts which are arranged in parallel, eachpair being closed by depression of one of a series of selector buttons,the second solenoid being provided with normally closed contacts whichare opened when the second solenoid is energized and which are in serieswith the self-holding contacts of the first solenoid.

8. A selector panel according to claim 1 wherein a locking bar ismovable longitudinally of the guideway and is spring biased in onedirection, and each key in the series is provided with a locking armwhich, when the key is depressed, engages a projection on the lockingbar to move the locking bar against its spring bias and then latchesbehind the projection to hold the key depressed.

References Cited UNITED STATES PATENTS 3,168,240 2/1965 ONeal 235-54FOREIGN PATENTS 523,954 4/1931 Germany.

STEPHEN I. TOMSKY, Primary Examiner U.S. c1. X.R. 235-26

